diff options
| author | Bill Gatliff <bgat@billgatliff.com> | 2007-05-31 22:02:22 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2007-07-12 11:13:33 +0100 |
| commit | 9d20fdd58e74d4d26dc5216efaaa0f800c23dd3a (patch) | |
| tree | bc8520791f304ce297a52f575930c2797067521c /arch/arm/kernel/head-common.S | |
| parent | 7d09e85448dfa78e3e58186c934449aaf6d49b50 (diff) | |
[ARM] 4423/1: add ATAGS support
Examines the ATAGS pointer (r2) at boot, and interprets
a nonzero value as a reference to an ATAGS structure. A
suitable ATAGS structure replaces the kernel's command line.
Signed-off-by: Bill Gatliff <bgat@billgatliff.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/head-common.S')
| -rw-r--r-- | arch/arm/kernel/head-common.S | 40 |
1 files changed, 37 insertions, 3 deletions
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S index a52da0ddb43..024a9cf469b 100644 --- a/arch/arm/kernel/head-common.S +++ b/arch/arm/kernel/head-common.S @@ -20,7 +20,8 @@ __switch_data: .long _end @ r7 .long processor_id @ r4 .long __machine_arch_type @ r5 - .long cr_alignment @ r6 + .long __atags_pointer @ r6 + .long cr_alignment @ r7 .long init_thread_union + THREAD_START_SP @ sp /* @@ -29,6 +30,7 @@ __switch_data: * * r0 = cp#15 control register * r1 = machine ID + * r2 = atags pointer * r9 = processor ID */ .type __mmap_switched, %function @@ -47,11 +49,12 @@ __mmap_switched: strcc fp, [r6],#4 bcc 1b - ldmia r3, {r4, r5, r6, sp} + ldmia r3, {r4, r5, r6, r7, sp} str r9, [r4] @ Save processor ID str r1, [r5] @ Save machine type + str r2, [r6] @ Save atags pointer bic r4, r0, #CR_A @ Clear 'A' bit - stmia r6, {r0, r4} @ Save control register values + stmia r7, {r0, r4} @ Save control register values b start_kernel /* @@ -215,3 +218,34 @@ ENTRY(lookup_machine_type) bl __lookup_machine_type mov r0, r5 ldmfd sp!, {r4 - r6, pc} + +/* Determine validity of the r2 atags pointer. The heuristic requires + * that the pointer be aligned, in the first 16k of physical RAM and + * that the ATAG_CORE marker is first and present. Future revisions + * of this function may be more lenient with the physical address and + * may also be able to move the ATAGS block if necessary. + * + * r8 = machinfo + * + * Returns: + * r2 either valid atags pointer, or zero + * r5, r6 corrupted + */ + + .type __vet_atags, %function +__vet_atags: + tst r2, #0x3 @ aligned? + bne 1f + + ldr r5, [r2, #0] @ is first tag ATAG_CORE? + subs r5, r5, #ATAG_CORE_SIZE + bne 1f + ldr r5, [r2, #4] + ldr r6, =ATAG_CORE + cmp r5, r6 + bne 1f + + mov pc, lr @ atag pointer is ok + +1: mov r2, #0 + mov pc, lr |